/**
* EasyDrag 1.5 - Drag & Drop jQuery Plug-in
*
* Thanks for the community that is helping the improvement
* of this little piece of code.
*
* For usage instructions please visit http://fromvega.com/scripts
*/

(function($) {

    // to track if the mouse button is pressed
    var isMouseDown = false;

    // to track the current element being dragged
    var currentElement = null;
    var Direction = [];
    // callback holders
    var dropCallbacks = {};
    var dragCallbacks = {};

    // bubbling status
    var bubblings = {};

    // global position records
    var lastMouseX;
    var lastMouseY;
    var lastElemTop;
    var lastElemLeft;

    // track element dragStatus
    var dragStatus = {};

    // if user is holding any handle or not
    var holdingHandler = false;

    // returns the mouse (cursor) current position
    $.getMousePosition = function(e) {
        var posx = 0;
        var posy = 0;

        if (!e) var e = window.event;

        if (e.pageX && e.pageY) {
            posx = e.pageX;
            posy = e.pageY;
        }
        else if (e.clientX && e.clientY) {
            posx = e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft;
            posy = e.clientY + document.body.scrollTop + document.documentElement.scrollTop;
        }

        return { 'x': posx, 'y': posy };
    };

    // updates the position of the current element being dragged
    $.updatePosition = function(e) {
        var pos = $.getMousePosition(e);
        var spanX = (pos.x - lastMouseX);
        var spanY = (pos.y - lastMouseY);
        if (Direction[currentElement.id] == "all") {
            $(currentElement).css("left", (lastElemLeft + spanX));
            $(currentElement).css("top", (lastElemTop + spanY));
        }
        else if (Direction[currentElement.id] == "x") {
            $(currentElement).css("left", (lastElemLeft + spanX));
        }
        else {
            $(currentElement).css("top", (lastElemTop + spanY));
        }
    };

    // when the mouse is moved while the mouse button is pressed
    $(document).mousemove(function(e) {
        if (isMouseDown && dragStatus[currentElement.id] != 'false') {
            $.updatePosition(e);
            if (dragCallbacks[currentElement.id] != undefined) {
                dragCallbacks[currentElement.id](e, currentElement);
            }
            return false;
        }
    });

    // when the mouse button is released
    $(document).mouseup(function(e) {
        if (isMouseDown && dragStatus[currentElement.id] != 'false') {
            isMouseDown = false;
            if (dropCallbacks[currentElement.id] != undefined) {
                dropCallbacks[currentElement.id](e, currentElement);
            }

            return false;
        }
    });

    // register the function to be called while an element is being dragged
    $.fn.ondrag = function(callback) {
        return this.each(function() {
            dragCallbacks[this.id] = callback;
        });
    };

    // register the function to be called when an element is dropped
    $.fn.ondrop = function(callback) {
        return this.each(function() {
            dropCallbacks[this.id] = callback;
        });
    };

    // disable the dragging feature for the element
    $.fn.dragOff = function() {
        return this.each(function() {
            dragStatus[this.id] = 'off';
        });
    };

    // enable the dragging feature for the element
    $.fn.dragOn = function() {
        return this.each(function() {
            dragStatus[this.id] = 'on';
        });
    };

    // set a child element as a handler
    $.fn.setHandler = function(handlerId) {
        return this.each(function() {
            var draggable = this;

            // enable event bubbling so the user can reach the handle
            bubblings[this.id] = true;

            // reset cursor style
            $(draggable).css("cursor", "");

            // set current drag status
            dragStatus[draggable.id] = "handler";

            // change handle cursor type
            $("#" + handlerId).css("cursor", "move");

            // bind event handler
            $("#" + handlerId).mousedown(function(e) {
                holdingHandler = true;
                $(draggable).trigger('mousedown', [e]);
            });

            // bind event handler
            $("#" + handlerId).mouseup(function(e) {
                holdingHandler = false;
            });
        });
    }

    // set an element as draggable - allowBubbling enables/disables event bubbling
    $.fn.easydrag = function(allowBubbling, direction) {

        return this.each(function() {

            // if no id is defined assign a unique one
            if (undefined == this.id || !this.id.length) this.id = "easydrag" + (new Date().getTime());

            Direction[this.id] = direction || "all";
            // save event bubbling status
            bubblings[this.id] = allowBubbling ? true : false;

            // set dragStatus 
            dragStatus[this.id] = "on";

            // change the mouse pointer
            $(this).css("cursor", "move");

            // when an element receives a mouse press
            $(this).mousedown(function(e, b) {
                if (!b) {
                    b = e;
                }
                // just when "on" or "handler"
                if ((dragStatus[this.id] == "off") || (dragStatus[this.id] == "handler" && !holdingHandler))
                    return bubblings[this.id];

                // set it as absolute positioned
                $(this).css("position", "absolute");

                // set z-index
                $(this).css("z-index", parseInt(new Date().getTime() / 1000));

                // update track variables
                isMouseDown = true;
                currentElement = this;
                // retrieve positioning properties
                var pos = $.getMousePosition(b);
                lastMouseX = pos.x;
                lastMouseY = pos.y;

                lastElemTop = this.offsetTop;
                lastElemLeft = this.offsetLeft;

                $.updatePosition(b);

                return bubblings[this.id];
            });
        });
    };

})(jQuery);